This section is meant to serve as a refresher. The bulk of this class will be covering ways of organizing data as collections of primitive data types.
Primitive data types are like the concept of atoms in biology. This is the most basic building block of all data structures - it defines the type of value captured. Primitive data types are built into just about all the mainstream programming languages and typically store a single value.
Under the hood, data is stored into memory as bits (1's and 0's). When you define a variable, you are assigning space to certain values. When you define a variable with the type, you're indicating to type of value organized. The memory can then be filled with data or state.
Examples: integer, real, char, string.
In Java, because it was designed as a statically-typed language, you must first declare variables (i.e. reserved names) before the can be used. Statically-typed also means that you cannot change the type of value.
int i = 1; // defining an integer int j; // reserving the name String s = "Hello World!; // declaring a string value named s
Keep in mind that Java is sensitive to the scoping of variables.